Flame-retardant cable

Abstract

The invention relates to a flame-retardant cable having improved reaction to fire performances, in particular a reduced or null dripping under fire. The cable has a transmissive core and an outermost layer made from a flame-retardant polymer composition comprising: a) 100 phr of polyvinylchloride (PVC) as base polymer; b) 65-90 phr of a metal hydroxide; c) 2-9 phr of antimony trioxide; d) 1-3 phr of an optionally surface-modified sepiolite, and e) 3-10 phr of a Ca/Zn stabilizer.

1 . A flame-retardant cable having a transmissive core and an outermost layer made from a flame-retardant polymer composition comprising:
 a) 100 phr of polyvinylchloride (PVC) as base polymer;   b) 65-90 phr of a metal hydroxide;   c) 2-9 phr of antimony trioxide;   d) 1-3 phr of an optionally surface-modified sepiolite, and   e) 3-10 phr of a Ca/Zn stabilizer.   
     
     
         2 . The flame-retardant electric cable according to  claim 1  which is an electric cable having a transmissive core comprising an electric conductor and an electrically insulating coating ( 12 ). 
     
     
         3 . The flame-retardant electric cable according to  claim 1  which is an optical cable with a transmissive core comprising at least one optical fibre. 
     
     
         4 . The flame-retardant electric cable according to  claim 1  which is an opto-electric cable with a transmissive core comprising at least one optical fibre, an electric conductor and an electrically insulating layer. 
     
     
         5 . The flame-retardant electric cable according to  claim 1 , wherein the polymer composition further comprises up to 20 phr of an alkali or alkaline-earth metal carbonate. 
     
     
         6 . The flame-retardant electric cable according to  claim 1 , wherein the outermost layer is a jacket. 
     
     
         7 . The flame-retardant electric cable according to  claim 1 , wherein the outermost layer is a skin layer. 
     
     
         8 . The flame-retardant electric cable according to  claim 7 , wherein the skin layer surrounds a jacket, wherein the jacket is made of a flame-retardant polymer composition comprising:
 a) 100 phr of polyvinylchloride (PVC) as base polymer;   b) 65-90 phr of a metal hydroxide;   c) 2-9 phr of antimony trioxide;   d) 1-3 phr of an optionally surface-modified sepiolite, and   e) 3-10 phr of a Ca/Zn stabilizer.   
     
     
         9 . The flame-retardant electric cable according to  claim 7 , wherein the skin layer surrounds a jacket made from a flame-retardant PVC-based polymer composition lacking sepiolite. 
     
     
         10 . The flame-retardant electric cable according to  claim 1 , wherein PVC is the sole base polymer of the polymer composition. 
     
     
         11 . The flame-retardant electric cable according to  claim 1 , wherein the metal hydroxide is selected from magnesium hydroxide, aluminium hydroxide or a combination thereof. 
     
     
         12 . The flame-retardant electric cable according to  claim 1 , wherein the amount of antimony trioxide is in the range of 5-8 phr. 
     
     
         13 . The flame-retardant electric cable according to  claim 1 , wherein the sepiolite is surface-treated with an ammonium salt, silane such as silicone or a combination thereof. 
     
     
         14 . The flame-retardant electric cable according to  claim 5 , wherein the amount of the alkali or alkaline-earth metal carbonate is in the range of 15-20 phr. 
     
     
         15 . The flame-retardant electric cable according to  claim 1 , wherein the polymer composition further comprises at least one chlorinated paraffin plasticizer and at least one phthalate plasticizer in a ratio of from 1:2.0 to 1:3.5.